Preheat oven to 350°F (175°C). Grease and flour a 9-inch round cake pan.
In a large bowl, cream together the butter and sugar until light and fluffy. Beat in the eggs one at a time, then stir in the vanilla.
In a separate bowl, sift together the flour, baking powder, and salt. Beat the dry ingredients into the wet ingredients alternately with the orange juice and tangerine juice. Stir in the tangerine and orange zests.
Pour the batter into the prepared pan. Bake for 45 minutes, or until a toothpick inserted into the center of the cake comes out clean.
Let the cake cool for 10 minutes before removing from the pan. Allow to cool completely before serving.
Interesting Facts
Tangerines and oranges are both members of the citrus family, and are related to lemons, limes, and grapefruits.
Tangerines are often sweeter than oranges, and their skins are thinner and easier to peel.
The tangerine-orange combination adds a unique flavor to this cake, and the freshly grated zest gives it a distinct citrus flavor.